Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Base emitter voltage and collector current

  1. Aug 2, 2014 #1
    Does decrease in value of base-emitter voltage decreases collector current..??
    As I studied that decrease in base-emitter voltage of some part of signal to lesser ammplification of that part due to smaller current..but how base emitter voltage is leading to less collector current..
    because if base-emitter voltage decrease , base current increase which further increase collector current..
     
  2. jcsd
  3. Aug 2, 2014 #2

    NascentOxygen

    User Avatar

    Staff: Mentor

    Yes.

    If VBE decreases, base current decreases. It's a p-n junction, so the characteristic is that of a p-n junction diode. If the forward voltage increases, the forward current increases.
     
  4. Aug 2, 2014 #3
    But base-emitter voltage is a barrier voltage.. so if it decreases , base current should increase..!!!
     
  5. Aug 2, 2014 #4

    dlgoff

    User Avatar
    Science Advisor
    Gold Member

  6. Aug 2, 2014 #5
    But is'nt there any logic behind it...??
    because if we see this equ.
    Ib=Vb/Rb - Vbe/Rb
    so from this equ. it can be seen that if Vbe increase base current decrease..!!!
     
  7. Aug 2, 2014 #6

    jim hardy

    User Avatar
    Science Advisor
    Gold Member

    have you ever run across the formula for current through a junction,
    I=eqv/kt
    where v would be your Vbe ?
    That's what dlgoff's graph is showing you.


    that involves not only Vbe but an external Vb and an external Rb.

    Your original question
    did not involve either.

    It is important to be rigorous in your thinking. Focus on the junction, after you've figured it out then add the external components.

    Base current and collector current are related by the transistor's Beta,
    which itself is a function of collector current.........
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted
Similar Discussions: Base emitter voltage and collector current
Loading...